Binary subtraction for
Binary numbers addition is straight forward, while binary subtractions involve three fundamental steps. Detailed discussions to understand when to discard carry and when to take 2s complement of final result is
summarized in a table at end.
Binary Subtraction: Suppose, M is Minuend and N is subtrahend, Then, M – N can be done based on following three steps:
Step 1: Take 2’s complement of N and add it to M.
M – N = M + (2^n – N)
Step 2: If M is greater than or equal to N then end carry is discarded from the result.
M –N = M + (2^n – N) – 2^n
Step 3: If M is less than N then take 2’s complement of the result and append negative ‘-
solved example to explain binary subtraction is discussed next.